Redmi Note 8 2021 boliba Fix Imei Null By DFT Pro
1- turn off the phone completely, then open the DFT Pro tool, go to the Xiaomi tab, then Fastboot, then Services

2- click on Erase nvram (MTK) option and then go to the phone, press the volume down button + the volume up button and connect the phone, after the process is completed successfully the imei will back, but the imei is random

3- Close the phone completely again and open the MTK Auth Bypass tool. After opening the tool, click on the Diable Auth option, then go to the phone and press the volume down and volume up button and connect the phone, and wait until the tool recognizes the phone and gives us a reading showing that we can Continue without Auth protection as in this image (or similar reading)

Note: Do not close the MTK Auth Bypass Tool, but download it to the bottom (Minimize) because it must be open until all steps are completed

4- Open the Maui Meta 10th Edition tool, click on the Connect option, and wait for the tool to be recognized on the phone

5- Go to the search box in the tool and choose IMEI Download and write the second IMEI

6- After successfully writing the second IMEI, click on the Disconnect option to restart the phone to normal mode

Note: Tested on MIUI Global 12.5.1.0

ADDITIONALLY SEE 
NOTE 8 BOOTLOADER UNLOCK FILE